Systematics Section / ASPT
Sheidai, Masoud .
Cytogenetic Evolution of Several Grass Genera in Iran.
Cytogenetic studies were performed on several populations and species of wildly growing Poaceae taxa in Iran including Aegilops, Avena, Bromus, Stipa, Hordeum and Festuca, considering the ploidy level, chromosome behavior, chisma frequency and distribution, occurrence and the effects of B-chromosomes and cytogenetic mechanisms leading to the formation of unreduced gametes. Data showed the major role of chromosome number change and the occurrence of chromosomal structural changes particularly heterozygote translocations in the evolution of these species. Statistical analyses revealed a significant difference in the frequency and distribution of chiasmata among different populations and also different species indicating the occurrence of a major change in the genes controlling meiotic behavior of chromosomes among these taxa during their speciation. B-chromosomes occurred in many taxa which could significantly change the recombination index creating new genetic combinations in the next generation. Unreduced gametes were formed in most of the taxa studied through cytogenetic abnormalities including anaphase failure, Desynapsis and cytomixis. Such unreduced gametes may have played a significant role in the adaptation and speciation of taxa studied.
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1 - Shahid Beheshti University, Biology, Evin, Tehran, Tehran, Iran
Cytogenetic Evolution of Grasses.
Presentation Type: Oral Paper:Papers for Sections
Location: Continental A/Hilton
Date: Tuesday, July 10th, 2007
Time: 10:15 AM